This invention relates to a magnetic head. More particularly, the invention relates to fabricating a magnetic head that includes a high magnetic moment and a high resistivity magnetic seed layer adjacent to a magnetic core to improve the performance of the magnetic head.
Magnetic heads are used for magnetically writing and reading data on a magnetic storage medium, such as a disc, which moves relative to the head. A magnetic head includes an upper and lower yoke and pole which form the magnetic core of the head. Electrical conductors (or coils) pass through the core which are used for both reading and writing information onto the magnetic storage medium. A first seed layer is interposed below the lower yoke and a second seed layer is interposed below the upper yoke.
During a write operation, electrical current is caused to flow through the coils generating a magnetic field in the core. A gap region occupies a small space between the two pole tips of the magnetic core. The current flowing through the coils causes magnetic flux to span the gap region. The magnetic flux is then used to impress a magnetic field upon a storage medium producing a magnetic transition, which is then recorded.
There is a constant and ever increasing demand to process data in computer systems at increasingly higher rates. This demand places a corresponding burden on magnetic storage subsystems, including magnetic heads and storage media, to store data at a higher rate and over a higher density surface area. As a consequence, the materials used in the fabrication of magnetic heads and magnetic storage media need to handle the increased demand. In particular, the performance of magnetic heads can be affected by the magnetic properties of the materials used in the core material and in each seed layer.
As the data rate increases, the magnetic materials experience the negative effects of eddy currents and hysteresis. The effects of eddy currents are caused by the current flow induced in the core by a time varying flux. This undesirable effect causes the heating of the core and a subsequent degradation in the data rate of the head. In order to reduce and offset the negative effects of eddy currents, the magnetic material used in the seed layers that form the top pole of the upper core should exhibit a high resisitivity. However, current magnetic materials that are used in the seed layer portion of a magnetic head are inadequate.
Moreover, there is also an increasing demand to process more information over a smaller surface area of a magnetic storage medium. In order to process more data over the smaller surface area, the magnitude of the magnetic flux density must increase over the decreased surface area. This higher demand for a magnetic flux density requires that the magnetic material exhibit a high magnetic moment.
In addition, the magnetic material used in the seed layer of the magnetic head should exhibit high anisotropic properties. For example, the seed layer should exhibit soft magnetic characteristics such as the ability to be easily and quickly magnetized and demagnetized. Current materials employed in seed layers do not exhibit adequate anisotropic properties.
For the foregoing reasons, an improved magnetic head, in particular an improved magnetic seed layer, with high resistivity, high magnetic moment, and desirable anisotropic properties would be a significant improvement in the art.
In general, according to one aspect, the present invention features a magnetic head. The head includes a substrate, a non-magnetic seed layer deposited on the substrate, a bottom magnetic core piece positioned over and contacting the non-magnetic seed layer, a magnetic seed layer, a top magnetic core piece positioned over and contacting the magnetic seed layer, and a gap sandwiched between at least a portion of the bottom core piece and at least a portion of the magnetic seed layer.
Various aspects of the invention may include one or more of the following features. The magnetic seed layer may be a single layer comprising an alloy of Fe, Co, Zr, and Ta. Fe may be present in the range of 50 to 80 Atomic percent, Co may be present in the range of 20 to 50 Atomic percent, Zr may be present in the range of 1 to 10 Atomic percent, and Ta may be present in the range of 1 to 10 Atomic percent, and wherein the magnetic seed layer thickness may be in the range of 500 to 5000 Angstroms.
The magnetic seed layer may be a dual layer structure comprising a base layer and a top layer. The base layer may be an alloy chosen from the group consisting of NiFe, CoFe, NiFeCr, Ta, and TaN. The base layer alloy may have a thickness in the range of 5 to 500 Angstroms. The top layer may be an alloy including Fe, Co, Zr, and Ta. Fe may be present in the range of 50 to 80 Atomic percent, Co may be present in the range of 20 to 50 Atomic percent, Zr may be present in the range of 1 to 10 Atomic percent, and Ta may be present in the range of 1 to 10 Atomic percent. The magnetic seed layer may have a thickness in the range of 500 to 5000 Angstroms.
In another aspect, the invention features a method of fabricating a magnetic head. This method may include depositing a non-magnetic seed layer on a substrate, forming a bottom portion of a magnetic core on the non-magnetic seed layer, depositing a non-magnetic material on at least a portion of the bottom portion of the magnetic core, depositing a magnetic seed layer on the non-magnetic material, and forming a top portion of the magnetic core on the magnetic seed layer, the non-magnetic material forming a gap for the head.
In one implementation, depositing the magnetic seed layer may include depositing a single layer alloy consisting of Fe, Co, Zr, and Ta. Fe may be present in the range of 50 to 80 Atomic percent, Co may be present in the range of 20 to 50 Atomic percent, Zr may be present in the range of 1 to 10 Atomic percent, and Ta may be present in the range of 1 to 10 Atomic percent. The thickness of the magnetic seed layer may be in the range of 500 to 5000 Angstroms.
Depositing the magnetic seed layer may include depositing a dual layer structure comprising a base layer and a top layer. The base alloy may be chosen from the group consisting of NiFe, CoFe, NiFeCr, Ta, and TaN. The base alloy may have a thickness in the range of 5 to 500 Angstroms. The top layer alloy may be comprised of Fe, Co, Zr, and Ta. Fe may be present in the range of 50 to 80 Atomic percent, Co may be present in the range of 20 to 50 Atomic percent, Zr may be present in the range of 1 to 10 Atomic percent, and Ta may be present in the range of 1 to 10 Atomic percent. The magnetic seed layer may have a thickness in the range of 500 to 5000 Angstroms.
Depositing the magnetic seed layer may include using Dc-magnetron sputtering. The sputtering may be performed at a power of at least 500 Watts, a gas pressure of at least 10 milli-Torr, and a magnetic field based on a current, and may further include applying a magnetic field in the range of 50 to 200 Oersted.
Depositing the magnetic seed layer may also include post-annealing at a temperature in the range from 100 to 500 Celsius. The time duration of post-annealing, which is a function of the temperature, may range from 10 minutes to 100 hours. The post-annealing process may be performed after depositing the magnetic seed layer onto the magnetic head.
In yet another aspect, the invention features a magnetic head that includes a non-magnetic seed layer deposited on the substrate, a bottom magnetic core piece positioned over and contacting the non-magnetic seed layer, a means for increasing the magnetic moment and the resistivity of the magnetic head, and a top magnetic core piece positioned over and contacting the means.
In one implementation, the means for increasing the magnetic moment and the resistivity of the magnetic head can include a magnetic seed layer comprising a single layer of an alloy of Fe, Co, Zr, and Ta. Fe may be present in the range of 50 to 80 Atomic percent, Co may be present in the range of 20 to 50 Atomic percent, Zr may be present in the range of 1 to 10 Atomic percent, and Ta may be present in the range of 1 to 10 Atomic percent. The magnetic seed layer may have a thickness in the range of 500 to 5000 Angstroms.
In another implementation, the means for increasing the magnetic moment and the resistivity of the magnetic head may include a magnetic seed layer comprising a base layer and a top layer. The base layer may be an alloy chosen from the group consisting of NiFe, CoFe, NiFeCr, Ta, TaN. The base layer may have a thickness in the range of 5 to 500 Angstroms. The top layer may be an alloy of Fe, Co, Zr, and Ta. Fe may be present in the range of 50 to 80 Atomic percent, Co may be present in the range of 20 to 50 Atomic percent, Zr may be present in the range of 1 to 10 Atomic percent, and Ta may be present in the range of 1 to 10 Atomic percent. The magnetic seed layer may have a thickness in the range of 500 to 5000 Angstroms.
The invention may provide one or more of the following advantages. The presence of a high resistivity and high moment magnetic material in the magnetic seed layer adjacent to the magnetic core structure of the head may reduce the undesirable effects of eddy currents. As a result, the head may handle higher data rates. Moreover, the high moment property of the seed layer may enable the head to process data over a higher density storage medium. The addition of a post-annealing process upon the magnetic seed layer may further increase the magnetic moment of the magnetic seed layer and may allow the magnetic head to handle an even higher data rate.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.